Network communications have developed quickly over the last two decades. With the explosion of the Internet there is also an explosion in the speed requirements to process applications across the Internet. Many applications now include real-time voice and video and therefore have significant bandwidth requirements. However, there is still a large installed base of legacy technology that communicates at slow speeds. Since this legacy technology represents a significant capital investment, vendors prefer to keep this technology in place rather than substituting new technology. However, vendors also have the pressure to upgrade communication systems to provide end-users and service providers with the latest real-time voice and video capabilities. As a result, there is a need for compatibility between the legacy technologies and the newer technologies.
A number of communications standards have been promulgated by the Institute for Electrical and Electronic Engineers (I.E.E.E.) which address issues of compatibility between legacy devices and the newer communications devices as well as communications devices that come from different vendors.
One area of communications that has seen a significant amount of advancement is Local Area Networking (LAN) communications. There is an installed base of LAN's that communicate at 10 megabits per second. These systems represent the legacy technology. In addition, newer hardware is in place which is contemplated to communicate at gigabit speeds. In addition, in the middle of the far end technologies of 10 megabits per second and gigabit speed devices, is 100-megabit technology, which is also deployed.
As a result modem communications standards and systems have to accommodate communications between systems that have disparate technology (i.e. communicate at different speeds). In addition, it would be preferable to address the communications issues between these disparate technologies in an automated way without the need for human intervention such as toggling or modifying switch settings. Finally, it is preferable that this function be handled at the lowest possible level of the communications process. For example, using the Open System Interconnect (OSI) reference model layers of physical layer, data link layer, network layer, transport layer, session layer, presentation layer and applications layer. It would be preferable to place the functionality for addressing these disparate technologies at the lowest possible layer, such as the physical layer. Placing the functionality at this layer would open the higher layers to handling other functions and thereby improve the overall performance of the system.
While systems and standards are in place to negotiate some of the discrepancies (i.e. speed, protocols) between these disparate systems, many of these systems are not automated. In addition many of the systems require higher-level functionality sometimes depending on higher-level services in the applications layer to negotiate these discrepancies. Therefore, it is important to develop a system that negotiates the discrepancies between the newer systems and the legacy systems. In addition, it would be beneficial to do so utilizing the lowest possible layers of the OSI model for implementation.
In addition, even after mechanisms for enabling communications, such as standards have been developed, there may still be times when the systems don't operate properly. For example, there are times when communications devices do not operate at their highest possible speed because of wiring problems. Some standards place a length restriction on the cables used between devices. If the communications devices are connected with cables that are too long, the devices may communicate at a sub-optimal speed. In addition, the wrong cables may be used (i.e. 2 pairs of cables when 4 pairs of cable are required). Finally, flaws in the logic required for communications may cause a device to operate in a sub-optimal way. For example, if the equalizer is not working properly, a system that is designed to operate at 1000 megabits per second may only operate at 10 megabits per second.
As a result of the wiring or systems problems, the speed of communications between two devices may be drastically reduced. In other words, the speed that data can be communicated along the wire (i.e. wire-speed), may be reduced. Therefore, it would be beneficial to implement a technique that takes advantage of the maximum wire-speed available, when two devices are unable to communicate at the optimal (i.e. factory defined) speed.